How many moles of OH− are there in 2.758 g of Mg(OH)2?Give your answer in moles and to three decimal places.(Molar mass of  Mg(OH)2 = 58.32 g mol−1)

To find the number of moles in a given mass of a substance, you can use the formula:

Number of moles = mass of substance (in grams) / molar mass (in g/mol)

Given: Mass of Mg(OH)2 = 2.758 g Molar mass of Mg(OH)2 = 58.32 g/mol

Step 1: Substitute the given values into the formula:

Number of moles of Mg(OH)2 = 2.758 g / 58.32 g/mol

Step 2: Perform the division to find the number of moles of Mg(OH)2:

Number of moles of Mg(OH)2 = 0.047 moles

However, each molecule of Mg(OH)2 contains 2 moles of OH−. Therefore, to find the number of moles of OH−, we multiply the number of moles of Mg(OH)2 by 2.

Step 3: Calculate the number of moles of OH−:

Number of moles of OH− = 0.047 moles * 2 = 0.094 moles

So, there are 0.094 moles of OH− in 2.758 g of Mg(OH)2.